A medical electronic diagnostic or test device such as an EKG, electroencephalogram (EEG) or the like normally has a plurality of electrodes which must be positioned on respective locations on the body of the person being monitored. These electrodes form electrical contacts with the respective locations on the body, and allow readings of various functions to be taken.
German Pat. No. 1,939,523 and commonly owned equivalent U.S. Pat. No. 3,640,270 disclose a suction electrode for such an EKG or EEG. The electrode has a feed tube provided with a conductor, and terminating at its free end in a suction cup having a terminal connected to the connector and provided internally with a small jet pump. Normally a conductive jelly is applied to this suction cup, and compressed air is fed through the tube to the respective jet pump to form a low-pressure zone inside the suction cup. This allows the suction cup to be adhered tightly to the body. A compressed-air source and jet pump are used rather than a simple suction pump, as such a suction pump would inherently suck in some of the conductive jelly applied to make a good electrical connection, and eventually this jelly would form a conductive bridge between the various electrodes and the suction pump. The outlets of each of these jet pumps will emit small amounts of the conductive jelly, along with the air creating, via the jet-pump effect, the low-pressure zone that adheres the respective suction cup in place.
It is standard practice simply to plug the tubes into respective sockets on the EKG. These sockets can be set up so as to supply compressed air to the respective feed tubes, while making the electrical connections necessary for the respective electrodes.
Such an arrangement often leaves a tangle of feed tubes and wires that must be painstakingly sorted out each time the apparatus is used. Furthermore the designers of the equipment must constantly trade off lead length for the electrodes with efficiency, as when long pneumatic lines are provided for the electrodes pressure losses are a constant problem, and electrical problems frequently develop when the long electrical leads pick up transient signals from adjacent electronic equipment or magnetic devices. Providing short leads minimizes these problems, but on the other hand makes it necessary to virtually nestle the patient up to the EKG, a situation which makes its operation relatively difficult.
Another disadvantage with these systems, in particular when used in an EKG, is that the equipment employed is relatively bulky and hard to handle. Normally the EKG is used in combination with an oscilloscope that displays whatever process is being monitored. This oscilloscope, and the EKG, have relatively large power supplies whose transformers must be provided with expensive MU-metal shielding. It is therefore normal for this equipment to be mounted on several rolling tables whose transportation to the use location is complex. The relatively heavy equipment on top of light-duty tables becomes very top-heavy, so that extreme care must be exercised in rolling about such equipment.